Researchers say overnight exposure to low levels of artificial
light – like from a TV or computer monitor in a darkened room – likely increases
your risk for depression.

And even staying up late at the computer or in front of the
TV might elevate your odds of the disorder.

The Study

Researchers at Ohio State University separated a group of
female hamsters into two study groups.

The first group lived in an environment with 16 hours of
full light and 8 hours of darkness

The second group lived with 16 hours of full light and 8
hours of dim light – equivalent to the light emitted from a TV in a darkened
room or the ambient overnight light level of a major city

After 4 weeks, all hamsters were tested for animal measures
of depression:

Appetite for sugar and willingness to swim when placed in
water

Neurochemical measures

The Results

Hamsters exposed to dim overnight lighting had less
appetite for sugar water and were less willing to swim for survival when placed
in water.

The brains of the hamsters exposed to dim light showed evidence
of inflammation (which is strongly associated with depression) a reduction in
the release of melatonin and a reduction in the numbers of dendritic spines in
the hippocampus.

Symptoms of depression in the dim light group were reversed
after 2 weeks of sleeping again in full darkness.

Commentary

The researchers say that rising rates of depression over the
last 50 years may be partly attributable to the huge increase in overnight light exposure over that same period.

But the good news, according to doctoral student and lead
researcher Tracy Bedrosian,is that "people who stay up late in front of the
television and computer may be able to undo some of the harmful effects just by
going back to a regular light-dark cycle and minimizing their exposure to
artificial light at night."

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